Asymmetric warfare? Asymmetric definitely. Warfare? Too Early.

A person, believed to be a man, entered the “sterile” area of the terminal at about 9:30am today via the exit doors from the baggage collection area.

…

[T]he man was spotted on closed circuit TV entering through the exit but security staff watching monitors lost track of him once inside the terminal. Thousands of people are now being cleared out of the terminal to be rescreened by security.

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The breach exposes a gap in the terminal’s security for which Qantas is responsible, as there is no security officers permanently stationed at the “out” doors to watch passenger movements.

"We have security staff in that area but none permanently stationed at the doors, but obviously it shouldn’t have happened," Mr Woodward said.

Awww, shucks! Security breaches just shouldn’t have happened! The man should just do what he’s supposed to do. You know, just like computers always do: exactly and only what they’re supposed to.

Result?

Assessments of the number of people evacuated differs, with early unsourced reports as high as 5000 to 6000 people cleared out of the terminal.

An estimate from Melbourne Airport puts the number at up to 3000.

This is a fine example of asymmetric warfare. Cost of breach to the “perpetrator? Small. Cost to other passengers, Qantas, Melbourne Airport, … ? Huge.